There are still cameras with which users can obtain, adding to the standard film format pictures, pictures of other formats such as panoramic and HDTV (High-Density TV) format, and there are cameras which can use interchangeable lenses such as telephoto lenses and wide angle lenses having variable focal length.
In such a still camera, whenever the film format is changed or the lens is changed, the viewing area and size of the view finder frame must be changed according to the format or the lens in use to cover the proper viewing and picture taking areas.
FIG. 1 shows a typical viewfinder which is comprised of an object lens (1), a mirror lens (2), a reticle (frame line) lens (3) and an eyepiece lens (4).
To have more than one size of frame with a viewfinder matching with more than one film format or more than one interchangeable lens, the frames are usually provided on one reticle overlapping each other or placing a smaller frame in a bigger frame.
FIG. 2 shows typical frames provided on a reticle lens for three different kinds of film format, which is a frame for the standard 35 mm format (5), a frame for panorama format (6) and a frame for HDTV format (7), showing the viewing area of each format indicated by the frames provided on one reticle lens.
FIG. 3 shows the typical frames provided on a reticle lens for three different kinds of lens, which is a frame for standard lens (8), a frame for wide angle lens (9) and a frame for telephoto lens (10), showing the viewing area of each lens indicated by the frames provided on one reticle lens.
As shown by FIG. 2 and 3, if more than one frame is provided on a single reticle lens overlapping each other or with a smaller frame put in a bigger frame, users always see all of them simultaneously and may experience confusion, complication and difficulty of frame distinction.